With the allocation of a large amount of spectrum in the millimeter wave (mmW) range as an unlicensed band (e.g. the 60 Giga Hertz (GHz) band), there has been an explosion of activity to exploit both the huge amount of spectrum and its unlicensed nature. There is a great deal of harmonization of the 60 GHz band, but current regulations for the band place various limits on transmission (Tx) power, equivalent isotropically radiated power (EIRP), and other parameters. The Tx power limits are generally low. Even without low Tx power limits, it is still beneficial to operate at low power since high powered power amplifiers (PAs) in the mmW region can be expensive. To overcome the Tx power limits, high gain antennas, which typically focus in a limited range of direction from the antenna, may be used, for example in the Institute of Electrical and Electronics Engineers (IEEE) 802.11ad specifications. The low cost planar array antennas envisioned in IEEE 802.11ad and those currently used in WirelessHD™ devices may suffer from limited steering range, for example +/−45°. This range may be further reduced if passive sub-arrays for increasing array gain are used.
Multiple local area network (LAN) and personal area (PAN) standards for 60 GHz band have been created, including IEEE 802.11ad. Such standards may use channels that are approximately 2 GHz wide within the 60 GHz band, for example. The number of channels available may vary by region, for example, 2-4 channels.
For mobile devices that can operate over non-line-of-sight (NLOS) paths, a 360° directional coverage may not be needed, although benefits may be realized with increased coverage. For access points and backhaul applications, greater coverage up to 360° may be needed. This may be satisfied by use of multiple arrays or fixed antennas that each have partial coverage, but provide full coverage when combined provide. Alternatively, mechanical actuators may be used to either physically steer the array or physically move a reflector. Both VubIQ© and BridgeWave© have mmW antenna systems that employ mechanical movements to either move the antenna or move a reflector.